As the usage of wireless networks, particularly wireless or WiFi networks, explodes, application performance is often dependent on the health of the WiFi network. In particular, when a WiFi network is congested, queues could build up at the WiFi network access point, leading to increased delay or packet loss. In turn, transport-layer protocols, such as TCP, and applications, such as telephony applications, interpret such increased delay or packet loss as a sign of congestion, and they back off their transmissions by slowing their sending rate. Real-time streaming applications, such as a telephony application, are very sensitive to delay, so they will back off sharply in the hope that doing so will help reduce the delay.
These transport-layer protocols and application-layers treat the network as a black box, without regard to whether the congestion is self-induced or because of other traffic. In the latter case, backing off is only likely to hurt the performance of a flow without any corresponding benefit in terms of reduced delay or packet loss.